Engineers were Tuesday checking the Tabqa dam west of Raqqa to assess damage as a result of US-led coalition air strikes in support of the Syrian Democratic Forces advancing on the ISIS stronghold. After capturing Tabqa air base last week, the SDF is fighting ISIS for control of the dam on the River Euphrates. Its reservoir and hydroelectric power station suppy large parts of Syria. The UN has warned that the dam’s collapse would cause massive flooding and a humanitarian catastrophe across Raqqa province as far downstream as Deir ez-Zour. Since its capture in 2014, ISIS has maintained headquarters and other facilities at the dam, believing the coalition would never bomb it.